Concentration of minerals



W. O. BORCHERDT CONCENTRATION oF MINERALS May 8,1923. N 1,454,838

Filed March 19, 1919 506W Cyass/ /e/ 'fir/v 6.5 mes/1 Patented May 8, 1923.-

UNITED STATES PATENT OFFICE.;

:WALTER o. BOECHENDT, oF AUs'nNvTLLE, VIRGTNIA, AssIGNoE To 'THE NEW .TEEsEY zINc eoMPANY, or NEW Yoan, N. Y., A coRroEATroN or NEW JERSEY.

CONCENTRATION OF MINERALS.

Application filed March 13, 1919. Serial No. 283,628.

To all whom it Imay concern: I Be it known that I, WALTER O. BORCHERDT a citizen of the United States, residing at A ustinville, in the county of 'ythe, State of Virginia, have invented certain new and useful Improvements in the Concentration of Minerals; and I do hereby-declare the following to be a full, clear, and exact descrip-` tion of the invention, such as will enable others skilled in the art to which it appertalns to make'and use the same.

This invention relates to tlie concentration of ores by otation.

siderable amounts of colloids or colloidal, yshines are thus present itis usually necessary to operate in a more dilute pulp; or the froth produced is rendered thick, viscous and difficult to break down or reliquefy and to handle in launders, pumps and pipes, in which condition', it is spoken of as being over-Stabilized, because of its content of colloids Aor colloidal slimes, and gives'a dirty concentrate.

It has been proposed to treat such ore pulps, containing considerable amounts of colloidal slimes, with a coagulatingor fiocculating agent, in order to neutralize in part theobjezftionable effect of such slimes; but the coagulated or fiocculated constituen s remain admixed with the ore pulp and o. n seem to form therewith adsorption compounds or colloidal complexes wherewith the mineral particles are entangled or enmeshed and the flotation operation prejudiced thereby, as Well as, in some instances by the coagulating or flocculating agents which remain in sof lution in the ore pulp. Y The colloidal matters present in an ore pulp are probably derived for the most part from the gangue particles of the ores, although it is not unlikely that valuable mineral particles may also be present in the pulp in the form of colloids. Such colloidal matters may also be introduced with the milling water which is used to form the ore pulp, and this source of colloidal matters may be considerable during periods of heavy rainfall, when surface waters containing mud and other suspended matters, and heavvsources from which such colloidal matters are derived. Thus, for the purposes of the present invention, the colloidal constituents may be considered as ranging from just above the molecular size upward through the class of .so-called suspensoids, which, while possibly not true colloids, still, because of their relatively large specific surface,'exhibit some, if notv all, of the properties of colloids, and are capable of existing in both the sol or lgelstate, or of being dispersed and 'coagulated, or {iocculated and defiocculated. By a colloidal slime, therefore, I mean a material which is not necessarily a true colloid, but exhibits colloidal vcharacteristics to a sufiicient degreeh'to make it amenable to -the manipulation hereinafter described.

. As the result of my investigations, I believe that the injurious action on the otation operation of colloidal matters present in the ore pulp may result merely from their presence in the ore pulp, or may be due to their attachmfent to, or adsorption by, the'flo tation agent, or the gaseous iotation med- ;ium, or the mineral particles, or allthree. It is my belief that these. colloidal matters interfere with the flotation operation wheth-A er they exist in a fiocculated (or coagulate'd.) or in adeflocculated (or dispersed) condition, but I have found that in general their action is less marked 4when 4dispersed or deiocculated.

The'present invention in its broad aspect contemplates. as an improvement in the concentration of minerals by iotation, and as a. preliminary step to the flotation operatlon proper, the removal, in whole or in" art, of

colloidal constituents in a disperse or deiocculated condition from a mineral or o re pulp. .The removal of the c olloidal constltuents may be eiected in varlous ways. The'A present invention more -particularly relates to the removal of these constituents in a dispersed or deflocculated condition by sedimentation and decantation while in the process more'particularly described and claimed in my copending application Ser. No. 283,- 629 filed March 19, 1919 the removal of the colloidal constituents is effected by a. preliminary flotation operation in which a froth or scum containing part or the whole of the colloidal constituents, with -a relatively small proportion of the valuable minerals contained in the pulp, is separated from the bulk of the mineral ore pulp. After the removal of the colloidal constituents in accordance with the principles of the present invention the ore pulp is subjected to a flotation treatment in accordance with any of the usual practices.

The removal, by sedimentation and deeantation, from the mineral ore pulp of the colloidal constituents depends for its effectivene upon the relative differencein the rate of settling or sedimentation of the ore particles and the colloidal constituents. For this reason it is desirable to cause the colloidal constituents to settle at a much slower rate than the mineral and gangue particles in the ore pulp, whereby, after a predetermined settling of the mineral and gangue particles, any desired portion of the supernatant liquor containing the slower-settling colloidal constituents can be decanted in any suitable way to effect the F removal from the mineral ore pulp of the desired quantity of the colloidal constituents. In this connection, the present invention contemplates the dispersion or dellocculation of the colloidal constituents so as to cause them to settle at a very much slower rate than would be the case if they were coagulated or flocculated, so that they will remain in more 0r less permanent suspension in quiet pulp, thus permitting settling or sedimentation ofthe sands and slimes containing the valuable minerals, and decantation by displacement, or otherwise, of the water containing the suspended colloids or colloidal slimes.

The colloidal constituents of ore pulps are rarely, if ever, naturally deflo'cculated and dispersed to their maximum possible extent. Since aggregatedor flocculated colloid masses act like solid particles of greater magnitude the removal of the partially flocculated` colloidal constituents of an ore pulp by means of settling rocesses, or even washing with water on ta les or vanners, is generally incomplete and inadequate. --The agencies.

which promote the flocculation of the colloidal constituents of an ore pulp also in general seem to promote the adsorption or other form of attachment which exists between such colloidal@- constituents and the granular constituents-ofthe ore pulp. lt

follows, therefore, that when the colloidal constituents of an ore pulp have been thoroughly deflocculated land niinutely dispersed, they no longer exist in the form of aggregates resembling the coarser solid particles of the pulp, but behave more like substances in solution, and are, in fact, spoken of as being in colloidal solution, in which condition the forces tending to maintain them in suspension are greater than the effect of gravity, thereby greatly facilitating their separ-ation by' sedimentation and decantation', and as, at the same time, their adsorption or other bond for the coarser solid particles of the ore pulp is weakened, the removal of such colloidal constituents from the ore pulp is greatly facilitated over what is possible in their natural partially flocculated conditi-on.

Even when the colloidal constituents of the ore pulp are originally deflocculated or have been deflocculated early in the treatment of the pulp, they may have becomev (locculated during the treatment to which the pulp is subjected or agents may have been added which cause them to flocculate, and in such cases the same general method of treatment is applied to secure deflocculation in accordance with the principles of this'invention as would be applied to a ulp containing naturally flocculated colloidal constituents.

The present invention thus relatesto a process of concentrating such ore pulps as contain objectionable amounts of colloids or colloidal slimes, according to which the ore pulp is treated with a deflocculating or dispersing agent in order to convert the colloids or colloidal slimes into a deflocculated or dispersed state (if they are not already present in such a state of dispersion ordefloccula tion) and separating the dispersed or deflocculated colloids or colloidal slimes,z in Whole or in part, by decantation, or otherwise, from the ore pulp prior to the flotation operation. As a result of this removal of the colloids or colloidal slimes in a dispersed or deflocculated state,'the ore pulp is thereby freed from such colloidal matter, to the desired extent, so that the flotation operation can -thereafter be carried out without being prejudiced or inhibited by the colloidal constituents which have been removed.

I have found further. that for certain purposes, it is desirable to retain part of the colloidal constituents in the ore pulp. and that` when a proper amount of such constituents is present, it is possible to effect a differential separation, by flotation, of certain mineral constituents or "species of a mixed ore pulp, while the flotation lof other mineral constituents or species isf retarded or inhibited by the colloids or colloidal slimes: and that, thereafter, by a further removal of a part or all of the remaining colloids or colloidal slimes, in the manner above re- .f'erred to, flotation of other or the remaindone in the removal of colloids and colloidal slimes. prior to flotation, I am led toA believethat the colloidal constituents present in the ore pulps have an effect upon the flota- -tion operation, and the manner in which itl proceeds, which is comparable in importance to the effect which the oil employed has upon the flotation operation. Thus, where colloids or colloidal slimes are present in large amount, an over stabilized froth tends to be produced, which is difficult to break up and which gives a dirty concentrate, and which often leads to heavy losses of valuable minerals in the tailings, whereas, if fthe colloidal constituents are present in regulated amount, the flotation operation seems to be promoted thereby in many cases, 'these colloidal constituents cooperating with the oil and valuable mineral particles in producing a froth of the desired consistency; While it is also possible` by proper regulation of the colloidal constituents, to bring about a. differential flotation A of certain constituents, as above referred to.

As the result of the investigations which.

I have made I have been led to believe that colloidal adsorption takes place upon metallic surfaces and upon the surfaces of sulfides and other minerals, but that the strength of the adsorption varies considerably, depending upon the character of the colloid, its relative concentration, the kind and character of adsorbin material, and its temperature and condltion of electrical charge; that the combination of the colloids present .in many flotation pulps with the oil and other constituents of the froth, with the resulting production of a viscous or overstabilized froth and consumption of oil, is due to such colloidal adsorption; and that it is due, in'whcle or in part, tothe removal of such adsorbed colloids that the combination of the o il and air with the valuable minerals is facilitated, with resulting advantage to the flotation operation. I do not, however, desire, to limit myselfl by any theoretical explanation of the process of the present invention. Whateverl may be the correct explanation of the prejudicial effect of colloids when present, and of the advantages resulting from their removal, the process of the present invention involves such separation of the colloids, in Whole or inv part, (Whether adsorbed by or otherwise combined or admixed with the sulfides or other minerals) as a preliminary step to the flotation operation. n

Ifthe ore pulps contain the colloids or colloidal slimes in a naturally sufliciently dispersed condition, then the treatment with Will take a dispersing or 'deflocculating agent may not be necessary and the ore pulp may be subjected directly to vdifferential sedimentation or decantation for the removal ofthe colloidal constituents to the desired extent.

there will, of course, also be removed acorresponding portion of the water of the ore pulp. together with such constitutents as are dissolved therein.

If the colloidal slimes of the ore pulp are not naturally sufficiently dispersed, the ore pulp is treated with 'a dispersing or deflocculating agent to bringabout the desired dispersion or deflocculation, after which decantation is effected for the purpose of r'emoving aV portion or the whole of the dispersed colloidal slimes and accompanying water containing the added agent or agents. The dispersing agent which I have used to particular advantage with leadfzinc sulfid 'ores is sodium silicate, but, in general, other agents may be employed which will bring about thel desired dispersion or deflocculation, such, for example, as gum arabic known principles of colloid chemistry so With the 'removal of the colloidal 'slimesv that the desired deflocculation or dispersion y lace. Using sodium silicate, I have foun that good results have been obtained with an exceedingly small amount, for example, from 4 pounds down to a fraction of a pound of the sodium silicate per tonof dry ore treated.

The dispersion ofthe colloids (whether adsorbed by the mineral particles or other- Wise coagulated or flocculated)l may be promoted, or even brought about, to a greater `or less extent, by rapid circulation and agitation of the pulp, which will serve to distribute the deflocculating agent, if any is used, and cause abrasion of the mineral particles with each other and with floccules or coagules of colloidal matter in which thel mineral particles may be enmeshed, so that the separated and dispersed colloids may be more readily removed by d'ecantation. Increase in temperature may similarly be of assistance in bringing the colloids into a state permitting their removal `from the ore pulp. The optimum temperature, in the case of any particular ore, for effecting dispersion of. the colloidal constituents contained in the ore pulp may be determined by tests, in which the otherfactors are held constant and the temperature is varied through the range from" freezing up to boiling. Where this optimum temperature is higher than the normal temperature of' the ore pulp, the ore pulp may be heated to such' optimum temperature by direct heating or by the use of steam-heating coils, or by steam blown into the pulp, and Where this optimum temperature is found to be lower than the normal temperature of the ore pulp, the ore pulp may be cooled by dilution with cold water, by cooling coils, or by cooling towers.

I have found that an extremely convenient and effective Way of securing the necessary distribution of the dispersing or defiocculating agent through'the mass of the ore pulp, and of securing the desired degree of dispersion or de'fiocculation of the colloids or colloidal slimes present in said ore pulp, consists in adding the defiocculating or dispersing agent to the pulp at some point prior to the admission of the ore pulp to the ball or pebble mills, or other fine grinding machines. ISuch machines almost invariably form a part of the equipment of ore dressing plants, as a preliminary step in the process of preparing ores for treatment by flotation.

By so adding the deflocculating or dispersing agent to the ore pulp ahead of the fine grinding mills, the necessary mixture is secured Without inconvenience or added expense, and the dispersion or deiiocculation of the colloids or colloidal slimes may take place under the most favorable conditions of rising temperature and violent agitation. Under these conditions fioccules or coagules are readily broken up and prevented from re-forming, ar particles already coated with colloids or enmeshed Within floccules are cleaned or released; such colloids as are released from a solid or indurated condition by the grinding are immediately placed in the -dispersed or defiocculated state, and the fresh mineral surfaces exposed -by the grinding are prevented from being coated with inhibitory coatings of colloidal material. This procedure may with some ores be sufficient to effect the desired degree of deliocculation without the use ofa deflocculating agent, provided the decantation of the colloidal constituents is effected immediately after the pulp leaves the grinding machine, butv While the pulp is quiescent.

Whatever may be the preliminarytreatment, or combination of treatments, to which the ore pulp is subjected for the dispersion or deflocculation of its colloids, (in case such preliminary dispersion' is necessary) these colloids are, according tothe present invention, removed from the ore pulp, as by decantation, to the extent necessary to prevent them from interfering with the subsequent treatment of the pulp by flotation.

After the defocculated or dispersed colloids or colloidal slimes have been removed to the desired extent, that is, in whole or inpart, depending upon the result desired, the remainingore pulp, which is now in a more concentrated state, is diluted to the proper consistency and is then subjected to a flotation operation to secure separation of the valuable constituents from the Waste minerals. The removal of the colloids from the ore pulp often enables the ore pulp to be treated in a state of greater density, 'that is, in a more concentrated form, with the result that an increased tonnage of ore can be handledv byv a given plant.

If the original ore contains a mixture of valuable ingredients, such as sulfids, the process may be carried out `in' a number of stages 'in order to take advantage of the differential inhibition of the colloids or colloidal slimes toward the fiotation of certain of the minerals. For example, in a mixed and iron, the ore pulp may be treated 4for the removal of a portion only of the colloidal slimes in the manner above referred to, so that there will be retained sufficient of the colloids to prevent any considerable flotation of theviron and zinc sulfids While permitting the fiotation of the lead sulfid, so that a lead concentrate can be obtained relatively free from zinc and iron. The ore pulp is then treated for the removal of an additional portion of the colloidal slimes, so that, for example, flotation of the zinc is permitted, or flotation of the zinc and iron. Where the zinc is fioated Without flotation of the iron, a still further removal of the colloidal slimes may then be effected in order to permit fiotation of the iron,` sulfd. In carrying out differential flotationv of the different constituents, advantage may also be taken, ineach case of the Well known selective qualities of certain oils, or other flotation agents, for the various constituents, such selective qualities supplementing the selectively inhibitory action ofthe colloidal constituents.

The colloidal slimes ,which are separatedk from theore pulp are commonly of a character such that they can be run to waste. In case, however, these slimes carry suliicient values, they may be themselves subjected to a further treatment for the recovery of, the values therefrom. For example, they may themselves be subjected to a further flotation treatment, for the separation of valuable constituents therefrom, or they may be coagulatedA and subjected to other treatment for the recovery of values.

The Water accompanying the removed colloids may be separated and recovered for reuse. The colloidal slimes contained therein may thus be coagulated, and settled or filtered out.- The water separated from the colloids may be-puried, if necessary, to free it from dissolved salts prejudicial to the flotation, or prejudicial to the maintenance of the 'desired state of dispersion ofthe colloidal matter in the ore pulp to which it may be subsequently added.

The process of the present invention may becombined with other than flotation operations. For example, the o re pulp may be subjected to a preliminary separation byA jigs, or subjected to other preliminary methods of treatment prior to the flotation operation. In such cases,- the colloidal slimes may be removed either just prior to the flotation operation or at some previous period of treatment of the ore pulp.; and the addition of the dispersing agent, where such addition is necessary or desirable, may similarly take place at any suitable point or points prior to the removal of the colloids,-so

l that Ithe colloids will be in a dispersed state at` the time of their removal. l

The invention will be .further illustrated I by the following more detailed description,

' fier.

' rolls and returned to the screens.

taken in connection with the diagrammatic ilow sheet of the accompanying drawing. will describe the process as applied to a zinclead-iron sulfid ore, with a dolomitic gangue, f

isiobtained Vand 1from which the over-4 flow slimes, the tailshand the mixed leadf zinc-iron sulfide middlmgs are separately removed. The tailings go to waste. The overflow slimes pass to a distributor and thence to a series of two cone tanks from which a portion of the colloidal slimes, which I will refer to as primary colloid, is removed by overflow decantation and` run to waste.v

The solids or thickened ore pulp then 4passes to a screw. classifier where it is combined with water and with a further small lamount of the sodium-silicate, for example, about one pound -per ton of original feed. The middlings from the Hancock jig pass to a Hardinge mill' and thence to the screw classi- From the'classifier the over-size is returned tothe Hardinge' mill, while the under-size (through 65 mesh) goes to a Dorr tank or thickener.

The small amount of sodium silicate combined with the ore pulp serves to bring about and maintain a dispersed condition of the colloids or colloidal slimes so that these may be removed, to thepdesired extent, by overflowv or .,decantation. Such removal may take place in tanks su'ch as those of the Dorr, Allen 0r 'Callow types. With the overflow there will be' removed a-corresponding amount of waterso that the orepul'p will thereby become thickened. j So much of the water may in fact be removed so that only suilicient water and. accompanying. slimes remain to permit thehandling of the pulp as by pumping and its preparation for the next step in the process. The colloids or colloidal slimes in the` operation illustrated in the accompanying flow'sheet, are in part removed inthe form'of the so-called, primary colloids, and in part in the form' of what IY will refer to as secondary colloids,'in the over-flow from the Dorr tank. I v

From the Dorr'tank, from which a part of the secondary colloids are removed and run to waste, or to a place'of further treatment,

the thickened ore pulp 'passes to a diaphragm .pump andthence to a centrifugal `pump, where it is diluted with water to the properv degree forflotation. It yis then passed to the first flotation cell which is indicated as #1 lead rougher, and in which a differential flotation of thev lead takes place I I with-the aid o f 'a suitable flotation agent,

`such as emulsified creosote oil. -2

From .the #1 lead Arougher the froth or concentratepasses to the #l lead cleaner from which the middlings are returned 'to the #l lead rougher while the froth or `concentrate passes to the`#2 lead cleaner from which the final lead concentrate is obtained,

`whilethe middlings are returned to the #l lead cleaner.

The tails from the #l lead rougher are `combined with a further small amount of sodium silicate, for example, about. one-half pound per ton, and with dilution water, and pass to another Dorr tank where the {dispersion of the colloids is completed and a further portion ofthe colloids separated by decantation or over-How and run to waste. The solids from the -Dorr tank pass, to a diaphragm pump .and thence to a ycentrifugal proper amount of waterand then pass to the zinc rougher cell in which tlotation o'f the zinc is effected with the aid of. a suitablel flotation agent 'or agents, for examsulfate. VThe tails'- from this rougher cell are run to wastewhile the froth or concentrate `is passed to the #1 zinc cleaner cell and the froth or convcentrate therefrom to the #2 cleaner cell from which the final zinc ple', emulsitied crude oil, pine oil and copper i115 concentrate is obtained. The middlings from the respective cleaner cells are returned to the preceding-cell for re-'treatment t The flotation cells indicated on the flow sheet as rougher cells, or cleaner cells, respectvely, may be of common construction, forexample, cells 4of the Callow t Minerals Separation, .J anney, or type,.and their operation may b e carried out in a manner similar to that commonly 'prac e, or the and K.y

iso

pump where they are diluted with the 1101 fiotation While sufficient of the colloids are retained to inhibit the flotation of Zinc, this vdifferential flotation being further promoted by-the characterof the oil employed. A further separation of the colloids is then efected so that their inhibiting action is sufficiently overcome and flotation of the zinc suliid permitted, this flotation operation being also promoted by the addition of a suitab e oil or other flotation agent. Y

It will be understood that other ores than lead and zinc ores can be treated ina simi-a lar manner and with proper selection of the agent or agents added for bringing about or maintainingthe dispersed state of the colloids, (where the addition of such agent or agents is necessary .for this purpose) depending upon the so-called colloidal charge, (whether electro-positiveor electro-negative), of the constituents of the ore pulp lbeing treated, this treatment being based upon tests made in accordance with the general principles of colloid chemistry. The agent or agents may thus be of an acid character, in case the colloidalconstituents are such as are dispersed by an acid reagent,or of an alkaline character,'if the preliminary tests indicate this 'to be desirable. agents may themselves partake of a colloidal character, as, for exampleysilicic acid or sodium or potassium silicates, or soaps which also display acid or alkaline characteristics, or the'y may be organic colloids, for example, gum arabic. l(acacia) in sniall amounts,=

may be added to promote the desireddispersion and separation of the colloids.-

It will be seen that the process of the present invention involves the separation,.from

the ore pulp, prior to the flotation, of colloidal constituents, so that the flotation operation is carried out" withoutinterference therefrom, or with such regulated action of the ,pulpA the remaining colloids as is desirable for the particular object in view, asin case a differential separation of .certain constituents is" desired/f' This preliminary separation may be' readily effected by a simple overflow or decantat'ionof the. dispersed colloids, waterV being subsequently `added to dilute separation. Where the colloids are not already present in 'a sufficiently dispersed state, a suitable agent for bringing them into such a state may be added, and the separation thereafter effected. `In each-case The agent or' if necessary to secure the desired there is 'separated from-.the ore pulp, along with the separated colloids, a corresponding -amountof the water with its dissolved constituents so that the ore pulp is also. freed from any objectionable constituents contained therein. This water, however, after a suitable purification, may be returned to the operation and used over and over again. A

The .decantationA may -be carried out on the counter-current principle by the use of a series of tanks arranged for counter-flow of the ore pulp and of theover-flow, so that a more or less complete separation of the colloids may be effected and the amount thereof regulated.

rlhe process of thepresent invention can also be applied to the treatment of concen trates, as well as to the treatment of the original ore pulp, either forv the purpose of effect-ing a re-treatment of the concentrates by flotation, or for the purpose of separating la mixed concentrateinto its different constituents. For example, a mixed concentrate containing lead and zinc sulfides in substantially the relative proportions in which they existed in the ore, together with colloidal slimeswhich have been Vcarried into in the manner above referred to for the dispersion and removal .of part of the colloidal constituents. The concentrate may then be subjected to `a flotation operation with the addition of a proper amount of water to give the required dilution, and with the addition of a small amount of a dotation agent which will promote the Hotation of the lead, and a lead Vconcentrate may be thus obtained.

Thereafter, the 'ore pulp may be given a fur- Y ther treatment for the separation of' further amounts of the colloidal constituents and again subcted to flotation with the aid of a suitable flotation agentor agents to give a zinc concentrate. As. theresult of such a re-treatment the mixed concentrate Willbeseparated intoits constituents, and

A'the froth and concentrate, may be treated further concentration thereof will be effected. A

. Where the mineral pulp or the concentrate'` contains in solution in the 'water thereof constituents which prevent dispersion o1' de- ,locculation. such ,constituents may be in part or in whole removed,ras by the removal of the-water from the ore pulp. prior to the' dispersion or deflocculation treatment, or they may be otherwise neutralized and rendered harmless by methods and agents which are generally known, and can 'be regulated by simple tests. For example, an excessive quantit of magnesium sulphate or of some other e ectrolyte in the pulp may inter-l fere with the proper actionof sodium silicate as a dispersng agent. Such acondition may be corrected bv washin'gthe ore for the removal of solubl salts. rWhe1-e the pulp is acid or where there is latent acidity due to the occulsion of sulphur dioxide, an alkali may be added to correct the acidity, whereby the sodium silicate is enabled to act in the desired manner.

The present invention'is applicable to different flotation processes and with various means or reagents or agents which are used to effect or facilitate flotation. Thus, while the invention has herein been more particularly described in connection with froth flotation, it is to be understood that the invention is equally advantageous in connectionl with surface film flotation processes, as Well as in connection with other processes involving the principles of flotation.

The present invention is of general application in the concentration or segregation by the flotation process of any materials amenable to treatment by such process.- Throughout the present specification and the ap'- pen'ded claims, I have used the terms ores and minerals to designate any material adapted to be treated by the flotation process, and it is'to be understood that these terms are intended to cover generically sulfides and Awith colloidal constituents, which comprises dispersing normally flocculated colloidal constituents in the mineral pulp, removing colloidal constituents in a dispersed or deflocculated condition from the mineral pulp. to an extent suflicient to reduce the flotationinhibitory effects thereof, and thereafter subjecting the remaining mineral pulp to a flotation operation.

2. The method of improvingthe flotation of minerals associated in a mineral pulp with colloidal constituents, which comprises treating the mineral pulp topromote dispersion or deflocculation of normally flee-5 culated colloidal constituents therein, then removing from the mineral pulp tothe desired extent the so dispersed or deflocculated colloidal constituents, and thereafter sub- 'jecting the .remaining mineral pulp to a flotation operation.

3. The method of improving'the flotation of minerals associated .in a mineral pulp with colloidal constituents, which comprises addingto the mineral pulp a dispersing or deflocculating agent for promoting dispersion or deflocculation of flotation-inhibitory colloidal constituents therein, removing to the desiredjextent the dispersed or deflocltation operation.

7. Thelmethod of improving the flotation persing normally flocculated Icolloidal constituents inthe mineral pulp, subjecting the mineral pulp to an overflow or decantation treatment for the removal therefrom of the dispersed or deflocculated colloidal constituents, together with a corresponding portion of the -water of the pulp, to an extentsufficient to reduce the flotation-inhibitory effects thereof, and thereafter subjecting the remaining mineral pulp to a flotation operation.V

5. The 'method of improving the flotation of minerals associated in a mineral pulp with colloidal constituents, Which'comprises adding to the mineral pulpa dispersing or deflocculating agent for promoting disper-- sion or deflocculation of flotation-inhibitory colloidal constituents therein, subjecting the mineral pulp to a decantation treatment for the removal therefrom to the desired eX- tent of the dispersed or deflocculated colloidal constituents together with a corre'- sponding portion of the water of the pulp, and thereafter subjecting the pulp to a flotation operation.

6. The method of improving the flotation `of minerals associated in a mineral pulp with colloidal constituents, which comprises treating the mineral pulp to promote dispersion or deflocculation of normally flocculated colloidal -constituents therein, removing` from the mineral pulp the dispersed colloidal constituents, together with a corresponding portion of the Water of the pulp, to. an extent sufficient to reduce the flotation-inhibitory effects thereof, and subjecting the mineral pulp, freed as aforesaid ofthe dispersed or deflocculated colloidal constit-uents, to a floof minerals associated in a mineral pulp with' colloidal constituents, which comprises dispersing normally flocculated colloidal constituents in the mineral pulp, removing the colloidal constituents in a dispersed or deflocculated condition flrom the mineral pulp to an extent sufficient to reduce thc flotation-inhibitory effects thereof. subjecting the remaining minera-l pulp to a flotation operation,l and subjectingI the removed colloidal constituents to appropriate theatment for recovering the values therefrom.

8., The method of improving the flotation,

of minerals associated in a mineral pulp with colloidal constituents, which comprises agitating and heating` the mineral pulp under conditions promoting dispersion or deflocculvation of normally flocculated colloidal constituents therein, removing the dispersed colloidal constituents from the mineral pulp to an extent -suflicient to reduce the flotation-inhibitory effects thereof, and thereafter subjecting the remaining pulp to a flotation operation.

9. The method of improving the flotation of minerals associated in a mineral pulp with colloidal constituents, which comprises agitating the mineral pulp under conditions promoting dispersion or deflocculation of normally flocculated colloidal constituents therein, removing the dispersed or deflocculated colloidal constituents froni the mineral pulp to an extent sufficient to reduce the flotation-inhibitory effects thereof, and thereafter subjecting the remaining pulp to a flotation operation.

10. The method of improving the flotation of minerals associated in a mineral pulp with colloidal constituents, which comprises heating the mineral pulp under conditions promoting dispersion or deflocculation of normally flocculated colloidal constituents therein, `removing the dispersed colloidal constituents from the mineral pulp to an extent sufficient to modify the flotation-inhibitory effects thereof, and thereafter subjecting the remaining pulp to a flotation operation. Y

11. The method of improving the flotation of minerals associated in a mineralv pulp with colloidal constituents, which comprises f agitating and regulating the temperature of the mineral pulpn the presence of a dispersingl or deflocculating agent for promoting dispersion or deflocculation of flotation-inhibitory colloidal constituents therein, removing to the desired extent the dispersed or deflocculated colloidal constituents from the mineral pulp, and thereafter subjecting the pulp to a flotation operation.

12. The method of improving the flotation of minerals associated' in a mineral pulp with colloidal constituents, which comprises agitating the mineral pulp in the presence of a dispersing or' deflocculating agent for promoting dispersion or deflocculation of flotation-inhibitory colloidal constituent therein,removing to the desired extent the dispersed or deflocculated colloidal constituents from the mineral pulp, and thereafter subjecting the pulp to a lflotationl opera-V tion.

13. The method of improving the flotation of minerals associated in a mineral pulp with colloidal constituents which comprises regulating the -temperature of'the mineral pulp in the presence of a dispersing or deflocculating agent for promoting dispersion or deflocculationof flotation-inhibitory col- 'loidal constituents therein, removingto the desired extent the dispersed or deflocculated colloidal constituents from the mineral pulp, and thereafter subjecting the pulp to a flotation operation.

14. The method of improving the flotation of minerals associated in a mineral pulp with colloidal constituents, which comprises subjecting the mineral pulp to a.

jecting the remaining pulp to a flotation operation.

15. The method of improving the flotation of minerals associated in a mineral pulp with colloidal constituents, which comprises subjecting the lmineral pulp to a grinding operation in the presence of a dispersing or deflocculating agent for kpromoting the dispersion or deflocculation of flotation-inhibitory colloidal constituents therein, removing to the desired extent the dispersed or deflocculated colloidal constituents from the mineral pulp, and thereaftersubjecting the pulp to a flotation operation.

16. The method of effecting the differential flotation of minerals from a mixedmineral pulp containing colloidal constituents, Which comprises removing apart of the colloidal constituents from the mineral 'pulp to permit flotation4 of one mineral` species thereof while retarding the flotation of others species, subjecting the mineral pulp to a flotation operation, removing 'a further amount of colloidal constituents from the mineral pulp to permit flotationv of a further mineral species, and subjecting the mineral pulp to a further flotation operation.

17. The method ofpefi'ecting the differential flotation of minerals from a mixedmineral pulp containing colloidal constituents, which comprises treating the mineral pulp to promote dispersion or deflocculation of normally flocculated colloidal constituents therein, 4removing from the pulp sufficient of the dispersed or deflocculated colloidal constituents to permit flotation of one mineral species ofthe pulp While retarding theflotation of another mineral species thereof, and subjecting the pulp to a flotationoperation.

18. rl`he ,method of effecting the dife-rential flotation of minerals from a mixedmineral pulp containing colloidal constituents, which comprises treating themineral pulp 'to promote dispersion or deflocculation of colloidal constituents therein, removing,

`mit flotation of certain of the mineral species of the pulp while-retarding the flot-a.-

tion of other mineral speciesthereof, s ubjectng the pulp to a dotation operation effectiuug a further removal from the remain ist ing pulp of colloidal constituents to permit the flotation of a further mineral species of the pulp, and subjecting the pulp to a further flotation operation.

19. The method of effecting the differential flotation of minerals associated in 'a mineral pulp with colloidal constituents, which comprises removing from the pulpa partof the colloidal'constituents to permit flotation of certain mineral species of the pulp while retarding the flotation of other mineral species thereof, subjecting the pulp to a fiotation operation with the aid of a flotation agent promoting the differential separation by. flotation,removing from the pulp a further portion of the colloidal constituents to permit the flotation lof other mineral species thereof, and subjecting the pulp to a further flotation operationl with the aid of a iotation agent'promoting the flotation of such other mineral species.

20. The method of improving the flotation of minerals associated in a mineralpulp with colloidal constituents, which comprises adding to the mineral pulp a small amount of sodium silicate for promoting dispersion or deflocculation of the colloidal constituents therein, subjecting the pulp to a decantation treatment to remove therefrom to the desired extent the dispersed or deflocculated `colloidal constituents together with a corresponding portion 'of the water of thev pulp, diluting the resulting mineral pulp, and subjecting the diluted pulp to a flotation operation.

21. The method of effecting the differential separation of lead and zinc sulfides from minerals containing the same and associated in a mineral pulp with colloidal constituents, which comprises removing from the pulp a portion of the colloidal constituents to permit flotation of the lead sulfide-while retaining suicient to retard flotation of the zinc sulfide,vsubjecting the pulp to a'otaition operation to effect fiotation of the lead sulfide, removing from the remaining'pulp a further portion of the colloidal constitu- \ents therein to ermit flotation of the zinc sulfide, and subjecting such remaining pulp to a further flotation operation to effect flotation Vof the zinc sulfide. l 22. The method of effecting the differential flotation of lead and Vzinc sulides from ores containing the same and associated in a mineral pulp with colloidal constituents,

which comprises addin to the mineral pulp an appropriate agent or promoting dispersion or defiocculation of the colloidal constituents, decanting from the mineral pulp a portion of the dispersed or deflocculated colloidal constituents suicient to permit otation of the lead sulfide while retaining sufcient to retard flotation of the zinc sulfide,

subjecting the ulp to a flotation operation with the aid Aoga flotation agent promoting the differential dotation of the lead sulfide,

removing from the remaining pulp a further portion of the colloidal constituents therein' to rmit flotation of the zinc sulfide, and subjecting such remaining pulp to a further flotation operation with the aid ofa flotation agent promoting the flotation ofthe zinc sul-v dispersion or deflocculation of the colloidall constituents therein, removing a portion of the dispersed or deflocculated colloidal constituents from the pulp by a decantation treatment with accompanying removal of a corresponding portion of the water of the pulp, diluting 4the pulp and subjecting it to a flotation operation withthe aid of a flotation a ent promoting the flotation ofthe lead sul de, adding to the remaining pulp a further small amount of sodium silicate and removing therefrom a further amount of the resulting dispersed colloidal constituents to permit fiotation of the zinc sulfide, and subjecting such remainingpulp to a further flotation operation with t-he aid of a flotation agent promoting the flotation of the zinc sulfide.

24. The methodof improving the otation "of minerals assoclated in a mineral pulp wlth colloidal constituents, whichvcomprises its temperature under conditions promoting dispersion or deflocculation of normally flocculated colloidal constituents therein, removing the dispersed colloidal constituents from the mineral pulp to an extent suliicient to reduce the lotat1on-inhibitory1-e1ects thereof, and thereafter subjectirigthe remaining pulp to a fiotation operation.

26. The method ofv effecting the concentration .by flotation of zinc sulfide from an ore containing the same and associated in a mineral pulp with colloidal constituents, which comprises treating the mineral pulp with sodium silicate; for promoting dispersion or deiocculaton of the colloidal constituents, removing to the desired extent-the dispersed or deocculated colloidal oonstituentsfrom the mineral Apul and thereaftersubjecting .the pulp to afotation operation to elect the` removal therefrom by notation ofthe ziincrsulide.v f x27. The method'of` improving the flotation of minerals -associatedin a mineral Apulp with colloidal constituents, which com#4 v after subjecting the pulp to a flotation -op-'S- .prises adding tothe mineral pulp. 'a smally -amount of sodium silicate for promoting `tration by iotationof lead sulfide. from an.

ore containing' the same and associatedl in a mineral pulp with colloidal constituents, vwhich comprises treating. the mineral pulp' with sodium. silicate vfor promoting .dispersion or" dclocculation of the colloidaliconvstituel'its,removing-to the desired extent Vthe dispersed Vor deflocculatedf.colloidalV -c'onstituents. from the mineral pulp, and thereerationv to elect the removal thereromby flotation of the lead-sulfide.

29.` T he method of improving the-'flotation of minerals associatedin amineral pulpV with colloidal constituents, Vwhich comprises dispersing or delocculating normallygflocf culated colloidal yconstituents therein, re moving.l the. dispersed or 'deocculatedcol loidal constituents from the mineral. pulp to an extentsuicient to reduce the lotatloninhibitory effects thereof, and thereafter( subjecting vthe remaining pulp lto a 'flotation operation. f y

,30. The method' of improving .the Z{iota-v tion .of-'minerals associated -in a mineral' pulp With-colloidal constituents, which comprises adding to the mineral pulpa dispersving, or detlocculating agent for promoting dispersion ordeiocculatlon of colloidal constituents therein, removing the. -dispersed or .deflocculated colloidal constituents from' the mineral lpull to an extent .sufficient to reduce the flotatlonlnhibltory effects therei- In testimony whereof' I aiiiir'msliE j Messes of, and thereafter subjecting -theremaining pulp to a iota'tionoperation'. '31.i'lhe method ot'improving-the flotation vof mineralsassociated in'-A aj mineral pulp' with colloidal constituents' which comprises adding to the mineral pulp a dispers- 'mg or deflocculati'ng a entferpromoting dispersion or delocculatlon of colloidal -constituents therein, subjecting the mineral pulp to a decantation treatment for the re movaltherefroin-of the dispersed. or. de.

looculated colloidal constituents, together with a corresponding portion ofthe water of the pulp, to an extent sullicient Ito reduce the flotation-inhibitory effects' thereof, and thereafter subjecting-the remaining pulp to a notation operation.

improving the` i flota- `tion of minerals associated in a `mineral pulp withcolloidal constituent`s,fwhich com-" prises .treating `the mineral pulp 'to promotev dispersion or deiiocculation' Aof normally Aloc'culated colloidal constituents therein, re-A .moving from themineral pulpthe so dis- .persed or deflocculated colloidal constituents,'together with a corresponding portion ofthe water of theV pulp,.to an extentzsuiicient toreduce the lotation-inhibitoryeffects thereof, diluting the remaining mineral pulp with substantiallycolloidl-free 4.'Watier,

and subjecting the diluted pulp to anota# tion operation; l

3 3. The methodof improving thelotation cf minerals associated in a mineral pulp with colloidal constituents, which comprises Aadding vto the mineral pulp a dispersing' or deflocculating agent rior promoting dispersion or delocc'ulation of `colloidal constitu- -ents therein, subjecting the mineral pulpto -a decantation treatment-for the r emoval". l therefrom. of thev soydispersed or dellocculated colloidal cons ,t'ii :uents, together withl a corresponding portion of the water of the pulp., to van extent suliicient to-reduce thelotation-inhibitory effectsv thereof, diluting the' remaining vmineral pulp 'with -colloid' free Water, and subjecting .the diluted .pulp to av flotationoperation. 

